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Dec. 17, 2007 -- Psoriasis is not generally thought of as life-threatening, but it just might be for those with the severest forms of the disease.

People with severe psoriasis had a 50% increased risk of death compared with people without the inflammatory skin disease in a newly reported study.

Men with severe psoriasis died an average of 3.5 years earlier than men without the condition, while women with severe psoriasis died 4.4 years earlier than women without psoriasis.

Having mild psoriasis was not associated with an increased risk of death, and the researchers did not have information on causes of death.

But researcher Joel M. Gelfand, MD, says the findings make it clear that patients with severe psoriasis are at greater risk than has been realized.

"To put this in perspective, this finding suggests that more years of life are lost related to severe psoriasis than to severe hypertension," he tells WebMD.

Psoriasis and Death

As many as 7.5 million Americans have psoriasis, according to the National Institutes of Health.

About 80% to 85% of patients have mild to moderate psoriasis, while 15% to 20% have more extensive skin involvement. These patients generally require treatment with systemic medications like the drugs methotrexate and cyclosporine or newer biologics such as Enbrel, Remicade, and Humira.

Using a national medical records database from the U.K., Gelfand and colleagues from the University of Pennsylvania School of Medicine identified 133,568 patients with mild psoriasis, defined as having a diagnosis of psoriasis but no history of treatment for the condition.

An additional 3,951 patients were identified with severe psoriasis.

For each patient, up to five people without psoriasis who visited doctors for other causes were used for comparison.

During the study period, the death rate among patients with severe psoriasis was almost twice as high as in patients without psoriasis (21.3 deaths per 1,000 individuals per year vs. 12 deaths per 1,000 individuals per year).

During the study period, patients with severe psoriasis had a 50% increased risk of death compared with those without psoriasis. Those with milder psoriasis didn't have an increased risk of death compared to those without psoriasis.

The study appears in the December issue of the Archives of Dermatology.

Is Inflammation to Blame?

Earlier research by Gelfand and others found that people with severe psoriasis are at increased risk for a wide range of chronic conditions, including heart disease.

Psoriasis is now widely believed to be an autoimmune disease involving inflammation and the accelerated growth of skin cells and blood vessels, which produce the swollen, red lesions characteristic of the condition.

"One theory is that this chronic inflammation impacts other organs and systems within the body," Elizabeth Horn, PhD, of the International Psoriasis Council tells WebMD.

Inflammation within the body is increasingly recognized as a major contributor to a host of life-threatening conditions.

"We know that chronic inflammation is bad for a variety of organs and that it is probably involved in a number of chronic diseases, including cardiovascular disease and diabetes," Gelfand says.

Horn says the latest research should serve as a wake-up call to patients and their doctors that severe psoriasis is a serious disease.

"We are learning that there is something happening in people with severe psoriasis that may not be happening with milder forms of the disease," she says.

Horn and Gelfand agree that patients with severe psoriasis need to be especially vigilant about taking care of their overall health.

"It is very important for these patients to see their internist regularly, to have age-appropriate screenings, and to have their cardiovascular risks assessed and treated, if necessary," Gelfand says.